As a known conveyor system, for example, JP-A 09-52621 (1997) discloses a conveyor system which will now be described. In the following description, a direction in which the article is conveyed with the conveyor system is referred to as a conveying direction and a direction perpendicular to the conveying direction on a plane is referred to as a horizontal direction.
The conveyor system comprises a body frame which constitutes a frame of the conveyor system and is arranged in the conveying direction, a driven shaft which is rotatably arranged in the horizontal direction at an upstream end of the conveying direction of the body frame, a driving shaft which is rotatably arranged in the horizontal direction at a downstream end of the conveying direction of the body frame, and a driving electric motor gear which is coupled to the driving shaft.
The body frame is formed by upper frame bars and lower frame bars respectively arranged on both right and left sides in the conveying direction, an intermediate frame member for coupling the right and left upper frame bars and lower frame bars, and a leg body arranged downward continuously from the right and left lower frame bars.
A pair of right and left sprockets are respectively arranged on the right and left ends of the driven shaft and the driving shaft, and a chain is arranged between the left sprocket of the driven shaft and the left sprocket of the driving shaft, and between the right sprocket of the driven shaft and the right sprocket of the driving shaft.
Further, multiple slats (guide bars) are attached between the right and left chains, with the horizontal direction being defined as a longitudinal direction, and a shoe (movable body), guided by the slat to freely reciprocate in the horizontal direction, is externally fitted over the slat.
According to the above configuration, when the electrical motor is driven to rotationally drive the driving shaft, both chains move by means of each sprocket, thus conveying the article provided on the slat in the conveying direction.
A branch conveyor, slanted outwardly and downwardly with respect to the conveying direction, is coupled at an external position on both right and left sides of the body frame, and by traversing the shoe group from one side to the other side in the horizontal direction while moving in the conveying direction, the article is laterally pushed and transferred to the branch conveyor.
However, the configuration of the above mentioned known conveyor system has the following problems.
When starting up the conveyor system, the chain positioned below the sprocket arranged on the driving shaft, that is, the return side chain moving in the direction opposite the conveying direction of the article, stretches thus causing the chain to hang down below the sprocket.
Further, if a supporting plate supporting the return side chain is arranged below the sprocket arranged on the driving shaft, when the chain hangs down below the sprocket, it contacts the supporting plate thus generating a contacting noise, which contacting noise becomes louder as the body length of the body frame becomes greater (longer) and the conveying speed becomes faster.